Method of straightening a deformed pipe string under compression in a well



INVENTORS.

MEDIUM JAMES V. LANGSTON, JOHN A. DIQDENE,

v T LE5 n Filed Aug. 17, 1964 J. V. LANGSTON ETAL UNDER COMPRESSION IN A WELL COMPRESSION BEND "E II METHOD OF STRAIGHTENING A DEFORMED PIPE STRING Nov. 22, 1966 coouNe United States Patent 3 286,769 METHOD 0F STRAIGHTENING A DEFGRMED PEPE STRING UNDER COMPRESSION IN A WELL James V. Langston, Luling, and John A. Diodene, Gretna,

La., assignors, by mesne assignments, to Esso Production Research Company, Houston, Tex., a corporation of Delaware Filed Aug. 17, 1964, Ser. No. 390,125 11 Claims. (Cl. 16639) The present invention is directed to the treatment of wells. More specifically, the invention is concerned with the treatment of the well having a string of pipe therein. More particularly, the invention is concerned with the method of treating a well having a pipe string therein which has become deformed.

The present invention may be briefly described as a method of treating a well having a pipe string therein whose ends are fixed and which has become deformed by compression to the extent that passage of tools through the pipe string is prevented. In the present invention the deformed pipe string is cooled a sufficient amount to shorten the deformed pipe string and thereby remedy the deformity. Thereafter, a well tool may be run through the pipe string.

In a well, tubular pipe strings such as tubing strings are suspended at the wellhead with the lower end of the pipe string set on a packer or anchor. This places the lower portion of the string in compression. Any increase in compression due to excess weight of the pipe string placedon the packer or anchor or any increase in aver- ,age temperature of the pipe string after it has been placed may result in corkscrewing and bending of that portion of the pipe string which is in compression. This deformation of the pipe string prevents passage through the pipe string of remedial work tools such aswire line fishing tools, concentric tubing strings, perforating tools, instruments such as bottom hole gauges and logging devices. Deformation of the pipe string by compression causes the tools or instruments to become stuck in the compression portion of the tubular string which may require pulling of the entire string to perform any remedial work or to recover any tools and the like which may become stuck in the deformed portion of the pipe string or below.

In accordance with the present invention, the bottom of the tubular string or any portion thereof which becomes deformed by compression is treated to shorten it and straighten the string by cooling at least the deformed portion of the string without movement of the pipe string from the wellhead. In other words, the two fixed ends of the string remain in position and the treatment of the well in accordance with the present invention allows the deformation to be remedied.

In accordance with the present invention, a tubing string such as a tubular pipe, which is usually a steel pipe and which has a coefficient of expansion, is cooled a sufficient amount to give the desired shrinkage or shortening in the length of the pipe string. Knowing the coeflicient of expansion, the temperature to which the pipe string must be cooled may be determined.

In accordance with the present invention, lowering of the temperature of the pipe string is effected by contacting the pipe string with a pre-cooled medium which may be a gas, a liquid or a solid. For temperatures above freezing the cooling medium may be fresh water or mud and for temperatures lower than the freezing point of water, a brine solution such as sodium chloride or saturated salt mud and the like, may be used. Other cooling media may be employed, such as oil, or a gas may be expanded in the pipe string which is under compression to cause cooling. A preferred method for cooling the pipe string is to flow a refrigerated or chilled liquid through the pipe string until the desired temperature is reached. For example, salt water may be cooled by mixing it with Dry Ice (solid CO and then employed in the pipe string to shorten it and to reduce compression. In accordance with the present invention, the pipe string may be cooled by pumping a refrigerated cooling medium down the tubular pipe string to displace fluid into the formation. Another method involves running a concentric tubing into the pipe string at least to a point adjacent the compression portion of the string followed by circulating the refrigerated cooling medium through the concentric tubing and upwardly through the pipe string or vice versa. Likewise, an opening which may be a valved opening may be provided in the pipe string such as a tubing string with the cooling medium circulated down the tubing string and upwardly in the annulus between the tubing string and the casing. Thereafter, on cooling the pipe string to relieve the deformity caused by compression it is then possible to run remedial workover tools and instruments through the pipe string.

The present invention will be further illustrated by reference to the drawing in which:

FIGURE 1 is an exaggerated view showing a well having a tubing string deformed by compression;

FIGURE 2 is a showing of a well after treatment in accordance with the present invention; and

FIGURE 3 illustrates another mode in accordance with the invention. 4

Referring now to the drawing in which identical numerals will designate identical parts and particularly to FIGURES l and 2, numeral 11 designates a casing arranged in a well b-ore drilled from the earth surface 12 to penetrate formation 13.

Arranged in the casing 11 is a tubing string 14 which is set in a packer 15 adjacent its lower end and which is suspended at its upper end from wellhead 16. The tubing string 14 above the wellhead 16 is provided with a Christmas tree generally designated by the numeral 17 and including a valve means 18. Connected to the Christmas tree 17 is a flow line 19 controlled by valve 20.

In accordance with FIGURE 1, the tubing string 14 has its upper end under tension and its lower end under compression such that the tubing string 14 becomes deformed to the extent that it has a bend B in its intermediate portion between its ends which prevents the free passage of tools through the tubing string 14.

In accordance with the present invention a cooling medium is introduced through flow line 19 into tubing string 1-4 to displace any fluid contained therein and to chill at least the deformed portion B. The displaced fluid and a portion of the cooling medium may be forced out into the formation 13.

Referring now to FIGURE 2, on cooling the deformed portion B or any portion of the tubing string it will be seen that the tubing string 14 shrinks and has become straightened to relieve the compression and to allow passage of a perforating tool illustrated by numeral 21 through the tubing string 14 on lowering it from the surface by means of wire line 22.

After the tool 21 has been lowered through the tubing string 14 and whatever remedial work performed which is necessary, the tubing string 14 may be allowed to warm up to formation temperature and return to its original tension and compression status as illustrated in FIGURE 1. If remedial work has to be performed thereafter,

the treatment of the well may be repeated.

Referring now to FIGURE 3, a different mode is illustrated. In accordance with FIGURE 3, the upper end of the Christmas tree 17 is provided with a flow line 23 controlled by a valve 24 with a concentric tubing string 25 run through a stufiing box 26 in a closure 27 forming part of the Christmas tree 17. The concentric tubing string 25 connects to a source of cooling medium. In this mode of the present invention the concentric tubing string 25 is lowered adjacent or to the top of the bent portion B of the tubing string 14 and thereafter a cooling medium is circulated through the concentric tubing string 25 and upwardly through the tubing string 14 and outwardly therefrom through flow line 23. Since the Area B is corkscrewed or bent, the concentric tubing 25 will not travel freely through this section of the production tubing; therefore, it should remain above bent portion B. The concentric tubing 25 depth in the tubing string will depend upon the length of that portion of the tubing string 14 in compression; i.e., the amount of shrinkage necessary to remove compression. To acquire a definite amount of shrinkage, the longer the portion of tubing string that is cooled, the higher the temperature of the coolant may be. Conversely, for the same definite amount of shrinkage of the tubing string 14, when a shorter portion of the string is in contact with the coolant, a lower temperature of the coolant is required. The treatment is continued until the tubing string 14 is relieved of the bent portion B and is substantially in the condition shown in FIGURE 2 whereupon a well tool may be run theret'hrough without becoming stuck after pulling the concentric tubing 25.

In order to illustrate the invention further, the following example is given:

. During a Workover of a well in a Southern Louisiana Field, a slack-off weight of 28,000 pounds and a pulling weight of 51,000 pounds to move 12,000 feet of 1" tubing in 2%" outside diameter tubing indicated that the hottom of the 2%" tubing string was in compression and therefore crooked. Efforts to locate tubing collars and perforate while using a line from which a gun was suspended were unsuccessful due to excessive drag on the line causing the collar locator to move with jerks. The

- collars were then located and the'well perforated with a gun using a line even though upward motion of the collar locator was unsteady and not smooth. Three days of swabbing failed to induce natural flow and during this time the temperature of the fluid in the annulus and tubing increased or approached the normal well temperature gradient. In an attempt to reperforate the well, the gun stuck in the 2% tubing at close to 13,000 feet. The gun was freed by pressuring the tubing to 5,000 pounds per square inch pressure and pulling 8,000 pounds on the wire line. The tubing string was then straightened and compression reduced by cooling the tubing to shorten the string. In this operation a 1" concentric tubing was run to nearly 12,000 feet and the well circulated 16 hours with water at a temperature of 61 F. until the water being returned to the surface was at a temperature of 68 F. A total of 75 barrels of 9 pounds per gallon salt water was cooled to 48 F. with one ton of Dry Ice and circulated into the 1" concentric tubing. The temperature of the salt water returned to the surface from the 1-2%" annulus was 58 F. Thereafter the 1" concentric tubing was pulled and the Well was perforated without noticeable drag on the wire line suspending the tubing gun.

The temperature of the cooling medium depends on the temperature of the pipe string which has become deformed due to compression. As an example, where the temperature of the pipe string may range from about 80 F. to about 234 F., the pipe string which has become deformed may be cooled by circulating a cooling medium having a temperature in the range from 48 F. in to about 58 F. out. The coefficient of linear expansion of steel 4 tubing ranges from about 6.0 10" to about 7.0 10* foot/foot/ F. Knowing the coeflicient of expansion and the temperature gradient in the well, the degree of cooling required to treat a well to temporarily shorten the pipe string and relieve compression may easily be determined- While the present invention has been described and illustrated with respect to a tubing string or pipe string, wherever any such terminology is employed, it is to be understood that any pipe string such as a casing, tubing string, or any tubular conduit having a coefficient of expansion which may become deformed or buckled due to having its ends fixed with one end under tension and the other end under compression is within the compass of the present invention.

The nature and objects of the present invention having been completely described and illustrated and the best mode contemplated set forth, what we wish to claim as new and useful and secure by Letters Patent is:

1. A method of treating a well having a string of pipe therein at least a portion of which is under compression and which has become deformed to the extent that passage of well tools therethrough is prevented which comprises cooling at least a portion of said pipe string a sufficient amount to shorten said pipe string and thereby induce tension and remedy said deformity in that portion of said pipe string which is under compression.

2. A method of treating a well having a string of pipe therein under compression at its lower end and under tension at its upper end and which has become deformed to the extent that passage of well tools therethrough is prevented which comprises circulating a cooling medium through said pipe string in a suflicient amount and at a sufficient temperature to cool and thereby shorten said pipe string and thereby restore tension and remedy said deformity in that portion of said pipe string which is under compression.

3. A method for treating a well having a string of pipe therein under compression at its lower end and under tension at its upper end and which has become deformed to the extent that passage of well tools therethrough is prevented which comprises cooling at least a portion of said pipe string a suflicient amount to shorten said pipe string and thereby induce tension and remedy said deformity in that portion of said pipe string which is under compression.

4. A method for treating a well having a string of pipe therein under compression at its lower end and under tension at its upper end and which has become deformed to the extent that passage of well tools therethrough is prevented which comprises contacting at least a portion of said pipe string with a cooling medium in a suflicient amount to cool and thereby induce tension and remedy said deformity in that portion of said pipe string which is under compression.

5. A method of treating a well having a string of pipe therein whose ends are fixed and which pipe string has become deformed by compression to the extent that passage of tools therethrough is prevented which com-prises cooling said deformed pipe string a sufficient amount to shorten said deformed pipe string and thereby remedy said deformity, and then running a well tool through said pipe string.

6. A method in accordance with claim 5 in which said pipe string is cooled by flowing a cooling medium through said pipe string.

7. A method in accordance with claim 6 in which the cooling medium is a chilled aqueous medium.

8. A method in accordance with claim 7 in which the cooling medium is chilled brine.

9. A method of treating a well having a pipe string therein whose ends are fixed and which pipe string has become deformed by compression to the extent that passage of tools therethrough is prevented which comprises flowing a cooling medium through said pipe string at a sufiiciently low temperature to reduce the temperature of 6 References Cited by the Examiner UNITED STATES PATENTS 2,033,560 3/1936 Wells 166-57 2,772,737 12/ 1956 Bond et al. 16639 X 3,186,971 5/1965 McEver et a1. 16639 X CHARLES E. OCONNELL, Primary Examiner.

S. J. NOVOSAD, Assistant Examiner. 

1. A METHOD OF TREATING A WELL HAVING A STRING OF PIPE THEREIN AT LEAST A PORTION OF WHICH IS UNDER COMPRESSION AND WHICH HAS BECOME DEFORMED TO THE EXTENT THAT PASSAGE OF WALL TOOLS THERETHROUGH IS PREVENTED WHICH COMPRISES COOLING AT LEAST A PORTION OF SAID PIPE STRING A SUFFI- 